The optional calculation can be used to find the total ampacity of a multifamily dwelling with natural gas cooking equipment.

The optional calculation can be used to find the total ampacity of a multifamily dwelling with natural gas cooking equipment.

• A. True
• B. Only for calculating lighting loads
• C. False
• D. Only if the dwelling uses electric cooking

Answer: (C)

Understanding load calculations helps you see why this statement isn’t correct. The optional calculation method in electrical design is a way to determine the dwelling’s electrical load using the actual connected loads instead of applying fixed demand factors. If cooking is gas, the electric cooking load is essentially negligible, so the optional method can produce a smaller total electric load than the standard method. However, that result is the calculated load (in amperes) you must supply with feeders and the service. You still must account for all other loads (lighting, receptacles, HVAC, etc.) and apply the code’s sizing rules. The final service ampacity isn’t determined simply by the optional calculation alone; you size the service to carry the calculated load, with appropriate conductor and equipment ratings. So, the statement is not correct.

Understanding load calculations helps you see why this statement isn’t correct. The optional calculation method in electrical design is a way to determine the dwelling’s electrical load using the actual connected loads instead of applying fixed demand factors. If cooking is gas, the electric cooking load is essentially negligible, so the optional method can produce a smaller total electric load than the standard method. However, that result is the calculated load (in amperes) you must supply with feeders and the service. You still must account for all other loads (lighting, receptacles, HVAC, etc.) and apply the code’s sizing rules. The final service ampacity isn’t determined simply by the optional calculation alone; you size the service to carry the calculated load, with appropriate conductor and equipment ratings. So, the statement is not correct.